This invention relates to a method for restoring used railroad ties having pre-existing spike holes, and more particularly to a method for plugging the pre-existing spike holes in the used railroad ties thereby forming the restored railroad ties which can be reused in rail replacement operations.
All maintenance of the rails in railroad operations typically means removing the rail spikes from the railroad ties. In many instances, these railroad ties are structurally usable because they have not deteriorated to a point requiring replacement. However, reusing these ties requires plugging of any spike holes existing in the railroad tie structure.
Generally, these spike holes can be plugged. In this way, when spikes are re-driven into the holes, the spikes will be firmly anchored within the confines of the ties.
In certain conventional practice, the ties are plugged by manually driving hardwood dowels into the spike holes. Unfortunately, the use of hardwood dowels results in several problems. First, the dowels do not completely fill the hole. This causes moisture infiltration during use that ultimately accelerates tie rot and in turn the deterioration of the railroad ties structure. Also, as compared with the original unused virgin railroad ties, the hardwood dowels do not effectively anchor the spikes into the structural railroad tie member.
The use of wood substrates and polymeric materials have been described in the prior art as follows: Method for Restoring Used Railroad Ties and the Restored Railroad Ties Formed Thereby (U.S. Pat. No. 5,952,072), Process For Producing Filled Polyurethane Elastomers (U.S. Pat. No. 5,952,053), Foamable Composition Exhibiting Instant Thixotropic Gelling (U.S. Pat. No. 6,455,605), Method of Filling Spike Holes in Railway Ties (U.S. Pat. No. 4,295,259), all of which are incorporated herein by reference.
It is desirable to provide an effective and efficient method for filling spike holes in used railroad ties which will then produce restored filled railroad ties which can be reused in rail replacement operations. Such a method should preferably have the following attributes: (a) firmly anchoring the spike into the tie; (b) deeply infiltrate the small cracks and crevices in the wood surface forming the spike hole to impede tie rot due to moisture; (c) bond tightly with the wood to prevent moisture infiltration; (d) be re-spikable within a relatively short time after dispensing; (e) displace standing water in tie holes during the hole filling operation; (f) dams leaky tie holes to enable complete filling. As for the filled portion of the railroad tie, it should anchor the spike in a manner which is comparable to introducing a railroad spike into the virgin wood portion of the subject railroad tie. Of particular importance is providing a filled spike hole which meets the needs described above but which is capable of allowing the railroad spike to effectively penetrate the filled material without substantial bending problems.